{
  "url": "https://openlegislation.uk/groundwater-regulations-northern-ireland-2009/schedule",
  "json_url": "https://openlegislation.uk/groundwater-regulations-northern-ireland-2009/schedule.json",
  "legislation": "nisr/2009/254",
  "legislation_title": "Groundwater Regulations (Northern Ireland) 2009",
  "legislation_url": "https://openlegislation.uk/groundwater-regulations-northern-ireland-2009",
  "path": "schedule",
  "kind": "schedule",
  "number": "1",
  "heading": "Groundwater Threshold Values",
  "text": "Table 1\nThreshold values for assessing groundwater chemical status\nParameter\nUnit\nTo examine if groundwater abstraction is causing saline or other intrusions\nTo examine if groundwater is providing a significant contribution to the failure of the environmental objectives of associated surface water bodies\nTo examine if the quality of groundwater that is abstracted for potable use is deteriorating, possibly resulting in a need for increased purification\nTo examine the spatial extent of a groundwater body or group of bodies that are exceeding an EU Standard or threshold value\n(1)The surface water environmental standards are set out in Schedule 1 to The Water Framework Directive (Classification, Priority Substances and Shellfish Waters) Regulations (Northern Ireland) 2015(S.R. 2015 No. 351).\n(2)The “dilution factor” is taken to be the fraction of the average annual river flow derived from groundwater inflows. It can be estimated from established hydrological indices such as the baseflow index, or from the ratio of catchment groundwater recharge to effective precipitation.\nAmmonium\nmg/l\n0.29\nArsenic\nμg/l\n7.5\nAtrazine\nμg/l\n0.075\nCadmium\nμg/l\n3.75\nChloride\nmg/l\n25\nElectrical Conductivity\nμS/cm\n800\n1875\nLead\nμg/l\n7.5\nMCPA\nμg/l\n0.075\nMecoprop\nμg/l\n0.075\nMercury\nμg/l\n0.75\nNitrate (as NO3)\nmg/l\n37.5\n37.5\nNitrite\nμg/l\n375\n375\nSimazine\nμg/l\n0.075\nSulphate\nmg/l\n187.5\nTetrachloroethylene\nμg/l\n7.5\n7.5\nTrichloroethylene\nμg/l\n7.5\n7.5\nAny pollutant in relation to which a surface water environmental standard has been set\n0.5 x (surface water standard divided by dilution factor)\nTable 2\nThreshold values for assessing the risk to wetlands\nColumn header\nAnnual mean nitrate concentration (mg/l NO3)\nAltitude Above Ordnance Datum\nWetland type\nup to 175 metres\nmore than 175 metres\nany\nQuaking bog\n18\n4\nWet dune\n13\nFen (mesotrophic) and Fen Meadow\n22\n9\nFen (oligotrophic and wetlands at tufa forming springs)\n20\n4\nWet grassland\n26\n9\nWet heath\n13\n9\nPeatbog and woodland on peatbog\n9\nWetland directly irrigated by spring or seepage\n9\nSwamp (mesotrophic) and reedbed\n22\nSwamp (oligotrophic)\n18\nWet woodland\n22\n9",
  "extent": "N.I.",
  "status": null,
  "version": "current",
  "annotations": [
    {
      "type": "F",
      "label": "F1",
      "text": "Sch. inserted (31.7.2014) by The Groundwater (Amendment) Regulations (Northern Ireland) 2014 (S.R. 2014/208), regs. 1, 12"
    },
    {
      "type": "F",
      "label": "F2",
      "text": "Sch. renumbered as Sch. 1 (31.12.2020) by The Water (Amendment) (Northern Ireland) (EU Exit) Regulations 2019 (S.I. 2019/112), regs. 1(1), 7(9); 2020 c. 1, Sch. 5 para. 1(1)"
    },
    {
      "type": "F",
      "label": "F3",
      "text": "Sch. Table 1 substituted (20.6.2016) by The Groundwater (Amendment) Regulations (Northern Ireland) 2016 (S.R. 2016/119), regs. 1(1), 5"
    },
    {
      "type": "footnote",
      "label": "f1",
      "text": "(1)The surface water environmental standards are set out in Schedule 1 to The Water Framework Directive (Classification, Priority Substances and Shellfish Waters) Regulations (Northern Ireland) 2015(S.R. 2015 No. 351)."
    },
    {
      "type": "footnote",
      "label": "f2",
      "text": "(2)The “dilution factor” is taken to be the fraction of the average annual river flow derived from groundwater inflows. It can be estimated from established hydrological indices such as the baseflow index, or from the ratio of catchment groundwater recharge to effective precipitation."
    }
  ],
  "outstanding_effects": [
    {
      "type": "inserted",
      "affecting": "nisr/2014/208",
      "affecting_title": "The Groundwater (Amendment) Regulations (Northern Ireland) 2014"
    },
    {
      "type": "substituted",
      "affecting": "nisr/2016/119",
      "affecting_title": "The Groundwater (Amendment) Regulations (Northern Ireland) 2016"
    },
    {
      "type": "inserted",
      "affecting": "uksi/2019/112",
      "affecting_title": "The Water (Amendment) (Northern Ireland) (EU Exit) Regulations 2019"
    },
    {
      "type": "Sch. renumbered as Sch. 1",
      "affecting": "uksi/2019/112",
      "affecting_title": "The Water (Amendment) (Northern Ireland) (EU Exit) Regulations 2019"
    }
  ],
  "provenance": {
    "source": "legislation.gov.uk",
    "source_url": "https://www.legislation.gov.uk/nisr/2009/254/schedule",
    "retrieved_at": "2026-10-29T01:31:10.101020+00:00"
  },
  "licence": "Open Government Licence v3.0",
  "licence_url": "https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/",
  "attribution": "Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives."
}